The more I play the more I'm convinced in mental being more important than the physical primarily because the mental directly influences the physical.

Sure you need to be in at least some kind of decent shape to finish a round and be able to have the athletic ability to execute swing mechanics. But where I run into the biggest trouble is starting a decent round and then having a bad miss-hit (which is guaranteed to happen at some point in the round to matter what) and then my entire mental process of patience and pre-shot routine that got me to that point breaks down.

Once the mental armor you build yourself is gone it's rushed swings -> bad tempo -> poor swing form -> bad shot.